body {
  font-family: 'Poppins', sans-serif;
  background-color: #eaf5fe;
  margin: 0;
  padding: 0;
  color: #333;
}

header {
  text-align: center;
  padding: 2rem 1rem;
  background-color: #1a73e8;
  color: white;
  border-bottom-left-radius: 30px;
  border-bottom-right-radius: 30px;
}

header h1 {
  font-size: 2.5rem;
  color: #fff;
}

.filter-section {
  display: flex;
  justify-content: center;
  margin: 1.5rem 0;
}

.filter-section select {
  padding: 10px 20px;
  border-radius: 10px;
  border: 1px solid #1a73e8;
  font-size: 1rem;
  color: #1a73e8;
  background-color: #fff;
  cursor: pointer;
  transition: all 0.3s ease;
}

.filter-section select:hover {
  background-color: #1a73e8;
  color: white;
}

.courses-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  padding: 2rem;
}

.course-card {
  background: white;
  border-radius: 20px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  padding: 1rem;
  text-align: center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
}

.course-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

.course-card img {
  width: 100%;
  height: 160px;
  object-fit: cover;
  border-radius: 15px;
}

.course-card h3 {
  color: #428cec;
  margin: 1rem 0 0.5rem;
}

.course-card p {
  font-size: 0.9rem;
  color: #555;
}

.tags {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 5px;
  margin-bottom: 0.5rem;
}

.tag {
  font-size: 0.75rem;
  padding: 5px 10px;
  border-radius: 12px;
  font-weight: 500;
}

.tag.beginner { background-color: #d0f0c0; color: #256029; }
.tag.intermediate { background-color: #fff4cc; color: #7a5e00; }
.tag.advanced { background-color: #fbd5d5; color: #b91c1c; }
.tag.age { background-color: #e3f2fd; color: #1565c0; }
.tag.category { background-color: #ede7f6; color: #4527a0; }

.back-btn {
  position: fixed;
  right: 30px;
  bottom: 30px;
  background-color: #3a6bac;
  color: #fff;
  border: none;
  padding: 10px 24px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 500;
  transition: background-color 0.3s ease, transform 0.2s ease;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.15);
  z-index: 1000;
}

.back-btn:hover {
  background-color: #345f9b;
  transform: translateY(-2px);
}